I’ve been having a little problem with spambots behind the scenes in the comments lately, although 99% of it got stuck in the moderation queue and never made it to the page.
I’ve still decided to add a CAPTCHA system to cut down drastically on the time it takes me to go through them and delete them. A CAPTCHA is that thing that shows you some distorted words you have to type in to prove you’re actually a human and not a spambot. I know they’re a bit annoying but it’s the better option for me than checking the site every 15 minutes, sorry.
To compensate for that annoyance I cut the requirement to fill in an e-mail address to comment, since the bots got that down anyways. The input field for an e-mail address is still there, but you only have to fill it out if you want to use a Gravatar in your comment. Generally e-mail addresses are only visible to me as the site admin and not to other visitors on the website.
Another measure against spambots is that any link posted in the comments (this does not apply to the Website URL field) makes a comment go into a moderation queue and only shows up on the page once I approve it. So be prepared that it might take a while for your comment to show up if it contains a link.
Now that sounds all terribly complicated but what you really only need to do to post a comment is:
• fill in your name
• type your comment
• solve the CAPTCHA
• post it